How do you enforce lowercase routing in ASP.NET Core?

Question

In ASP.NET 4 this was as easy as routes.LowercaseUrls = true; in the RegisterRoutes handler for the app.

I cannot find an equivalent in ASP

Answer 1

Update in ASP.NET Core Version >= 2.2

From ASP.NET Core 2.2, along with lowercase you can also make your route dashed using ConstraintMap which will make your route /Employee/EmployeeDetails/1 to /employee/employee-details/1 instead of /employee/employeedetails/1.

To do so, first create the SlugifyParameterTransformer class should be as follows:

public class SlugifyParameterTransformer : IOutboundParameterTransformer
{
    public string TransformOutbound(object value)
    {
        // Slugify value
        return value == null ? null : Regex.Replace(value.ToString(), "([a-z])([A-Z])", "$1-$2").ToLower();
    }
}

For ASP.NET Core 2.2 MVC:

In the ConfigureServices method of the Startup class:

services.AddRouting(option =>
{
    option.ConstraintMap["slugify"] = typeof(SlugifyParameterTransformer);
});

And Route configuration should be as follows:

app.UseMvc(routes =>
{
     routes.MapRoute(
        name: "default",
        template: "{controller:slugify}/{action:slugify}/{id?}",
        defaults: new { controller = "Home", action = "Index" });
});

For ASP.NET Core 2.2 Web API:

In the ConfigureServices method of the Startup class:

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc(options => 
    {
        options.Conventions.Add(new RouteTokenTransformerConvention(new SlugifyParameterTransformer()));
    }).SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
}

For ASP.NET Core >=3.0 MVC:

In the ConfigureServices method of the Startup class:

services.AddRouting(option =>
{
    option.ConstraintMap["slugify"] = typeof(SlugifyParameterTransformer);
});

And Route configuration should be as follows:

app.UseEndpoints(endpoints =>
{
      endpoints.MapAreaControllerRoute(
          name: "AdminAreaRoute",
          areaName: "Admin",
          pattern: "admin/{controller:slugify=Dashboard}/{action:slugify=Index}/{id:slugify?}");

      endpoints.MapControllerRoute(
          name: "default",
          pattern: "{controller:slugify}/{action:slugify}/{id:slugify?}",
          defaults: new { controller = "Home", action = "Index" });
});

For ASP.NET Core >=3.0 Web API:

In the ConfigureServices method of the Startup class:

services.AddControllers(options => 
{
    options.Conventions.Add(new RouteTokenTransformerConvention(new SlugifyParameterTransformer()));
});

For ASP.NET Core >=3.0 Razor Pages:

In the ConfigureServices method of the Startup class:

services.AddRazorPages(options => 
{
    options.Conventions.Add(new PageRouteTransformerConvention(new SlugifyParameterTransformer()));
})

This is will make /Employee/EmployeeDetails/1 route to /employee/employee-details/1